Several surface treatments have been developed in order to improve bone bonding of different biomaterials. In experimental animals hydroxyapatite (HA) coatings have been found to improve and speed up the formation of bone bonding. Therefore, the goal of most surface treatments has been to create HA on the materials' surfaces.
Firm bond between the implanted biomaterial and the surrounding soft tissue is, in many cases, far more important than improved bone bonding. A connective tissue capsule normally forms around the implanted materials within a few days. Thickness of the capsule varies depending on the material in question and the stage of healing. Epithelial lining separates all the implanted devices that penetrate skin or mucosa from the soft tissue components that are anatomically normal to the tissues in that area. A direct bond between the implant and soft tissues would be beneficial for several medical devices (e.g. dental implants, canyls, stents, external fixation pins). Until now no methods have been developed that can guarantee firm and safe integration between an implant and the soft tissues.